IP Library Granted Patent US 7,399,535
Granted Patent B2
US 7,399,535 · App. 11/254,641 · Granted Jul 15, 2008

Hot press-formed article

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Quick Facts
Patent No.
US 7,399,535
App. No.
11/254,641
Granted
Jul 15, 2008
Kind
B2
Abstract

A hot press-formed article having improved corrosion resistance and coating adhesion when coated is obtained by hot press forming of a zinc-based plated steel material. It has a zinc-based plating layer comprising an iron-zinc solid solution phase and atop it a zinc oxide layer. The average thickness of the zinc oxide layer which is the outermost layer is at most 2 μm. A hot press-formed article having a good appearance and excellent corrosion resistance, coating adhesion, post-coating corrosion resistance, and weldability has a layer ( 2 ) consisting essentially of an iron-zinc solid solution phase atop a base material steel sheet ( 1 ). It also has a zinc oxide layer ( 3 ) with an average thickness of at most 5 μm as an uppermost layer, but it does not have a substantial amount of an iron-zinc intermetallic compound phase. The total amount of Al contained in the iron-zinc solid solution layer ( 2 ) and the zinc oxide layer ( 3 ) is at most 0.5 g/m 2 , and/or the total amount of Al oxides contained in these layers is at most 5 mg/m 2 .

Claims (3)

1. A hot press-formed and quenched hardened article formed by hot press-forming of a zinc-based plated steel material and hardened by quenching of the zinc-based plated steel material after hot press forming or during hot press forming, a base steel layer of the hot press-formed article having on its surface a zinc-based plating layer which comprises an iron-zinc solid solution phase and which has a thickness of at least 1 μm and at most 50 μm, with the average thickness of a zinc oxide layer, which may be present atop the zinc-based plating layer, being at most 2 μm, wherein the zinc-based plating layer consists essentially of an iron-zinc solid solution phase, which is in contact with the base steel layer.

2. A hot press-formed article as set forth in claim 1 wherein substantially no zinc oxide layer is present atop the zinc-based plating layer.

3. A hot press-formed article as set forth in claim 1 wherein the total amount of zinc in the zinc-based plating layer and the zinc oxide layer present on the surface of the steel material is at least 10 g/m 2 and at most 90 g/m 2 .

Assignments (2)
MERGER Recorded May 14, 2019
From: SUMITOMO METAL INDUSTRIES, LTD.
To: NIPPON STEEL & SUMITOMO METAL CORPORATION
Reel/Frame 049165/0517 →
CHANGE OF NAME Recorded May 14, 2019
From: NIPPON STEEL & SUMITOMO METAL CORPORATION
To: NIPPON STEEL CORPORATION
Reel/Frame 049257/0828 →